Park Brake
3-3
Park Brake
Description and Operation
Park Brake System Description and
Operation
System Component Description
The park brake system consists of the following:
Park Brake Pedal Assembly:
Receives and transfers
park brake system apply input force from driver to park
brake cable system. Releases park brake system apply
force on vehicles without a park brake release handle
through the partial application of the park brake pedal.
Park Brake Release Handle Assembly
(If equipped):
Releases applied park brake system
when pulled.
Park Brake Cables:
Transfers input force received
from park brake pedal, through the park brake cable, to
park brake apply lever.
Park Brake Apply Pedal:
Multiplies and transfers
input force to park brake actuator.
Park Brake Actuator/Adjuster:
Uses multiplied input
force from apply lever to expand park brake shoe
toward the friction surface of the park brake drum.
Star wheel park brake actuators are also used to
control clearance between the park brake shoe and the
friction surface of the park brake drum.
Park Brake Shoe:
Applies mechanical output force
from park brake actuator to friction surface of the drum
in the park brake drum.
System Operation
The parking brake is a single drum design, mounted
around the propeller shaft, forward of the rear
differential. When the parking brake pedal is
depressed, the parking cable is pulled, overcoming
spring pressure within the parking brake and pushing
the brake shoes into contact with the inside of the
parking brake drum. When the operator disengages the
parking brake pedal, spring tension in the parking brake
pulls the park brake shoes to their
original (disengaged) position. The parking brake
self-adjusts for brake shoe wear by using a star wheel
mechanism.
2021 - Silverado 4500HD, 5500HD, and 6500HD Electrical Body Builder Manual
